Microwave absorbers are a kind of material that can effectively absorb incident microwave energy to make objects invisible to radar; therefore they are commonly used in aircraft cloaking and warship stealth. Recently, as radar detection devices have been improved to detect the near-meter microwave length regime, scientists are working on high-performance absorbers that can cloak objects in the equivalent ultra-high frequency regime (from 300 megahertz to two gigahertz). However, conventional absorbers for the ultra-high regime are usually thick, heavy or have narrow absorption bandwidth, making them unsuitable for stealth missions.
To solve this problem, a team of researchers from Huazhong University of Science and Technology in China has developed an ultra-thin, tunable broadband microwave absorber for ultra-high frequency applications. This ultra-thin absorbing surface, called an active frequency-selective surface absorber, consists of arrays of patterned conductors loaded with two common types of circuit elements known as resistors and varactors. The unit patterned cell absorbs microwaves and can also be actively controlled by stretching to expand the tunable bandwidth. In a paper published this week in the Journal of Applied Physics, from AIP Publishing, the researchers presented this work.
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